This invention relates to a test system for a mobile telecommunication system and, in particular, to a test system for use in measuring conditions of radio channels within each of radio service zones of radio base stations in the mobile telecommunication system.
A mobile telecommunication system comprises a mobile switching station, a plurality of radio base stations coupled to the mobile switching station and having radio service zones, respectively, and a plurality of mobile terminals freely moving in the radio service zones. A particular one of the mobile terminals currently is in a particular one of the radio service zones and communicates with a particular one of the radio base stations having the particular radio service zone through radio channels in the particular radio service zone to thereby perform communication with the mobile switching station through an up link and a down link including the radio channels.
The condition of radio channels is variable and affects the radio communication quality between the mobile station and the radio base station. The worst condition or obstacle of the radio channels disables the communication between them.
In order to measure conditions of radio channels in the radio service zones, JP-A-59 196633 discloses a remote testing apparatus which is connected to the mobile switching center. The remote testing apparatus comprises a central processing unit, a printer, a memory, a display terminal, a signal generator and a level meter. While, each of the mobile terminals is provided with a first loop back switch and a second loop back switch between a transmitting circuit and receiving circuit in the mobile terminal.
In testing, the remote testing apparatus originates a test call to a particular one of the mobile terminals to establish a down link and an up link between the remote testing apparatus and the particular mobile terminal through the mobile switching center and a particular one of the base stations having a particular one of radio service zones in which the particular mobile terminal currently exists. The particular mobile terminal is responsive to the test call to establish a test loop by connecting the down link with the up link through the first and the second loop back switches. Then, the remote testing apparatus sends out a test signal to the particular mobile terminal. The test signal is transmitted through the test loop and comes back to the remote testing apparatus. Thus, the remote testing apparatus can measure the entire characteristic of the down link and the up link. Thus, it is possible to know conditions of the radio channels in the particular radio service zone.
However, the known remote testing apparatus cannot measure conditions of the up and down links independently from each other.
Further, in use of the known remote testing apparatus, each of the mobile terminals must be provided with the first and second loop back switches and a function for driving the loop back switches in response to the test call. This unfortunately makes the mobile terminal expensive.
Moreover, the current mobile telecommunication system has no broadcasting system. Therefore, it is impossible to give information of the radio channel condition to a plurality of mobile terminals in the particular radio service zone.